Flush tank control



Feb. 4, 1941. w. J. |SON l 2,230,285

FLUSH TANK CONTROL Filed May 19, 1958 Flgfl. f/a l /3 ZNVENTOR W/L/AM d.COLL/50N ulllilll' FOR THE FIR/1 A Tron/vens Patented Feb. 4, 1941UNITED STATES PATENT OFFICE FLUSH TANK CONTROL William J. Collison,Bakersfield, Calif.

Application May 19, 1938, Serial No. 208,921

6 Claims.

My invention relates to flush tanks for toilets and the like, moreparticularly flush tanks having submerged discharge siphons, and isdirected to an improved form of siphon and improved means forcontrolling the action of the siphon. The present application is acontinuation-impart of my copending application, Serial No. 135,787,iiled April 8, 1937, entitled improvement in Flush tank with outletSiphon now matured into Patent 2,120,856.

Submerged discharge siphons, as heretofore employed in the art, havebeen characterized by sundry disadvantages. In some constructions thecontrol mechanisms are cumbersome or tend to get out of order, orinclude elements that must be renewed at frequent intervals; in otherarrangements, siphonic action is not reliable or is unduly delayed, orcauses excessive and obnoxions noise. The general object of my inventionis to avoid all of these disadvantages by providing a flush tankassembly in which the discharge Siphon is reliable in action,substantially free of objectionable noise and free of moving parts, andin which the siphon is controlled by a simple, positive, and foolproofcontrol mechanism.

A discharge siphon of the type to which my invention pertains has asinuous passage including at least two up-legs and an intermediate airtrap whereby the combined heads of the up-legs may balance pressure ofthe water submerging the Siphon, In the prior art, various expedientshave been employed for initiating discharge flow through such a siphon.In some arrangements, siphonic action is started by increasing the headof the water in which the siphon is submerged; in other arrangements theSiphon balance is upset by releasing the air trapped between the twoup-legs. The disadvantage of the first arrangement is excessive delay inthe siphonic action, and, in the second arrangement, numerousdisadvantages arise from the necessity of tubes and air-tight valves forremote control of the air trap. An object of my invention is toincorporate the first arrangement in a flush tank control in combinationwith liquid-discharge means eiective in the siphon itself to initiatesiphonic now, to the end that these two factors may cooperate to causeprompt siphonic action.

A more specic object of my invention with respect to theliquid-discharge means in the siphon is to have the single means serveboth the function of initiating siphonic discharge and the function ofrefilling the toilet bowl served after cessation of siphonic action.

A feature of my invention is the discovery that such a liquid-dischargemeans in the Siphon may be constructed and arranged to dischargesufficient volume with sufficient force to be effective for promptlyinitiating siphonic discharge without being effective to destroy therequisite air trap in the siphon while the flush tank is being refilled.

One specic object of my invention is to provide a substantiallynoiseless vent arrangement for admitting air to the air trap aftercessation of siphonic discharge; and a further and important object isto provide automatic and adjustable means for insuring freecommunication through such vent for a time interval adequate to providethe required quantity of air in the trap.

Another object of my invention is to provide an improved valve mechanismfor controlling the supply of water to the flush tank.

The above and other objects and advantages of my invention will beapparent from the detailed description to follow, taken with theaccompanying drawing.

In the drawing:

Fig. 1 is a longitudinal vertical section through a flush tankincorporating my invention;

Fig. 2 is an enlarged elevation partly sectioned of the valve mechanismof Fig. 1;

Fig. 3 is a view partly in section taken as indicated by the line 3-3 ofFig. 2;

Fig. 4 is an enlarged section showing the manual control of the valvemechanism;

Fig. 5 is a view taken as indicated by the line 5 5 of Fig. 4;

Fig. 6 is an enlarged side elevation of the discharge end of the relilltube employed in Fig. 1; and

Fig. 7 is a fragmentary vertical section through a siphon unit showingan alternative arrangement for the rell tube.

Fig. 1 shows a conventional toilet flush tank generally designated Iiihaving an outlet II and a cover or lid I2, the tank having the usualvent recesses I3 in its upper edge. Water is supplied to the tankthrough the usual stand-pipe I4, the discharge from which is controlledby a valve generally designated I5, the discharge passing from the valveinto a downwardly extending discharge pipe I6.

Water is discharged from the tank into a discharge pipe I9 at the portIl through a normally submerged discharge siphon generally designated2D. The Siphon 29 is of the type that has a continuous sinuous passageforming two up.legs and providing an air trap whereby the combined headsof the up-legs balance the nor'- mal pressure of liquid submerging theSiphon. The art is conversant with two types of siphons providing such auid balance, one type being formed simply by a pipe of sinuousconfiguration, the other type being formed by telescoped members ofcup-like configuration. Although it is to be understood that theprinciples of my invention are equally applicable to both types ofSiphons, the present disclosure will be limited to the latter type.

The drawing illustrates one manner in which such a Siphon may beconstructed. Extending upwardly into the tank is a cylindrical wall 2lthat is a continuation of the discharge pipe I9 and forms the innercylindrical wall of the siphon. Embracing this wall 20 with a watertightjoint is a cup-like member comprising an annular bottom wall 22 ofarcuate cross-sectional configuration and a cylindrical wall 23concentrically spaced from the wall 2l. Mounted on a spider 25 aroundthe inner Siphon wall 2| is an inverted cup member, generally designated26, that has an inner cylindrical wall 21 between the cylindrical wall2l and the cylindrical wall 23 and has an outer cylindrical wall 28 thatsurrounds the'cylindrical wall 23 in spaced relation thereto. Theinverted cup member 26 may be fabricated from Sheet metal in a mannerindicated in the drawing, the various parts being Stamped out with sheetmetal dies. In this particular construction the material that forms theinner wall 21 is flanged over as indicated at 29 and seamed to the upperedge of the outer cylinder wall 28. A disc 30, preferably of undulatingcross-sectional conguration, is then soldered into position, sealing thespace defined by the cylindrical wall 21. Finally, an annular sheetmetal wall 3| of arcuate cross-sectional conguration is inserted in theannular space between the walls 21 and 28 and soldered into place.

The described construction forms an annular Siphon passage of sinuouscharacter, which passage is divided into an outer up-leg 33, anintermediate down-leg 34, an-d an inner up-leg 35, the outer up-legopening from the interior of the flush tank and the inner up-legcommunicating with the discharge pipe I 9. It will be noted that in theconstruction shown, arcuate walls are provided at the various turns inthe siphonic passage to minimize friction.

In the normal submerged state of the Siphon with the water in the tankat a normal level 31, a state of equilibrium exists in which pressuresupporting the head of water in the inner up-leg 35 is transmitted byair under pressure in the down-leg 34 to the top of the Water column inthe up-leg 33 so that the heads of water in the two 11p-legs of thesiphon combine to balance the normal head of water in the tank eifectiveat the entrance to the up-leg 33, it being understood, of course, thatthe small column 38 of water at the bottom of the down-leg 34 lessensthe effectiveness of the head in the up-leg 35. It is apparent, then,that the down-leg 34 and the upper end of the up-leg 33 serve as an airtrap or air lock that is necessary for equilibrium with a submergedsiphon.

In the preferred form of my invention, a vent tube 4B extends downwardlyfrom the air trap of the siphon to a point near the level to which it isdesired that the water fall in the operation of the ush tank. Thedisposition of the vent tube 43 determines that level, because theadmission of air into the siphon when the liquid level of the tank issubstantially below normal breaks the siphonic action. Thus, with thevent tube 40 disposed as shown in Fig. 1, the Water in the tank Willdrop to approximately the level 4I before the siphon stream breaks.Subsequent rise in the water level seals the lower end of the vent tubelll and traps in the Siphon a quantity of air that is graduallycompressed above atmospheric pressure as the water level in the tankapproaches normal. It is apparent, then, that a quantity of air admittedinto the siphon through the vent tube 40 has, first, the function ofterminating the siphonic action and, later, the function of normallypreventing discharge flow through the Siphon.

For relling the bowl served by the iiush tank after the cessation ofsiphonic flow, I provide a rell pipe 43 that has one bend 44 below thelowest water level 4l and a second bend 45 above the normal water level31, the inlet end 45 of the rell tube extending into the discharge pipeI6 to receive ow therefrom. A feature of my invention is the conceptionthat this rell tube may be employed to initiate siphonic action eitheralone or in cooperation With some other ow-initiating means. In thepreferred form of my invention, the refill tube 43 enters the air trapof the Siphon from above and extends partially downward into thedown-leg 34 of the siphon. As best shown in Fig.f6, the discharge end ofthe rell tube 43 is, by preference, cut at an angle, the tip of the tubebeing bent to form a flange 41 across the path of flow to serve as abaille or diverting means to dissipate to a required extent the energyof the liquid discharge from the rell tube into the air trap.

The valve I5 includes a body 50 having integral therewith two bifurcatebrackets 5I and 52 for the valve control mechanism. 'I'hreaded into theVinlet portion of the valve body and serving as means for connecting thevalve to the standpipe I4 is a. bushing 53 that provides an annularvalve seat 54. Normally resting on the valve seat is a valve membergenerally designated 55, the valve member carrying the usual washer 55for contact with the valve seat. In the preferred form of my inventionthe valve member 55 includes a valve head 58 and a cylindricalvalveguide 59 that extends in a freely sliding manner through acylindrical portion 60 of the valve body. 'Ihe valve head 5B has a stem6I threaded into the valve-guide 53, and a suitable washer 52 may beretained between the valve head and the guide to minimize the ow ofWater out of the valve body around the valve-guide.

The mechanism for controlling the valve I5 includes a valve lever 63pivotally mounted by a pin 64 on the bracket 5I, with the swinging endof the lever extending between the arms of the bracket 52. The Valvelever 63 is adjustably related to the valve member 55 by means of ascrew 65 that extends through the valve lever in a position to abut theupper end of the valve-guide 59, the screw being adjustably secured by asuitable nut 65.

Mounted in the second bracket 52 by a pin 61 is a float lever, generallydesignated 58, that has a relatively long arm 59 carrying a float 10 anda relatively short arm 1I that extends over the valve lever 53.Extending through the long arm of the iloat lever is a screw 12 securedby a nut 13, the screw being disposed to move against/and thereby todepress the free end of the valve lever 53 when the oat approaches thelowermost water level 4I. Pivotally mounted on the arm 1I of the oatlever by a Suitable pin 14 is a bell-crank 15 having one arm 18 formedwith an integral ring 11 and a shorter arm 18, the shorter armpreferably carrying a roller 19. The ring 11 may be regarded as atrigger for releasing the valve, as will be later described.

While any suitable means may be employed to actuate this trigger, Iprefer to employ the' manually operable means shown in Figs. 4 and 5.EX-

tending through a suitable aperture 80 in the wall of the flush tank isa tubular member 82 that slidingly retains an operating plunger 83, thetubular member being secured by a suitable bushing 84. On the interiorof the tank is an angular lever 85 pivoted in a bracket 86 that isintegral with the bushing 84, the lever having an intermediate portion81 that swings. in the plane of the plunger and having an operating end88 that extends into the ring 11. The plunger has a suitable button 90on its external end and, preferably, is provided with a collar 9| ofrubber or other resilient material to cushion the movement of the buttonagainst the tubular member 82. The inner end of the plunger is cut awayto provide a suitably extensive longitudinal slot 92 that engages theintermediate portion 81 of the angular lever 85, a cotter pin 83extending across the end of the slot to prevent escape of the angularlever. Whenever the plunger 83 is shifted inwardly, it forces theangular lever 85 from the normal position of -the lever to the positionindicated by dotted lines in Fig. 4, which movement of the angular leverraises the ring 11 from its normal disposition to the position shown indotted lines in Fig. 2.

In the normal disposition of the mechanism between flushing operations,the plunger 83 is at its outermost position, as shown in Fig. 4, havingbeen moved to that position by gravitation of the angular lever 85. Theoperating end 88 of the angular lever extends through the ring 11 of thebell-crank 15, the bell-crank being in its normal disposition as shown'in full lines in Figs. 1 to 3. The short arm 18 of the bell-crank isdisposed at such an angle that it presses both against the bracket 52and against the valve lever 63 under force transmitted from the float10. It is apparent that the float keeps the valve l5 closed since thedownward pressure on the valve lever 63 exerted through the roller 18 istransmitted through the screw 65 to the valve-guide 53.

Inward movement of the plunger 83 caused by pressing the button 80causes the angular lever 85 to lift the ring 11, thereby tripping, thetrigger, since lifting of the rings swings the shorter arm 18 of thebell-crank to a disposition releasing the valve lever 63, as indicatedin dotted lines in Fig. 2. The releasing movement of the bell-crankcauses the float 10 to be slightly depressed, but subsequently thefloat, being out of operative engagement', with the valve, is free torise as additional water enters the tank. When the water reaches amaximum level such as indicated at 95, siphonic flow starts in theSiphon 20 and water passes into the discharge pipe I9.

Siphonic flow is occasioned by two independent factors, rst, theincrease in pressure head in the tank tending to overbalance the Siphonhead, and, second, the effect of the discharge from the refill pipe 43into the down-leg 34 of the siphon. Either one of these factors issufficient alone to initiate siphonic discharge from the tank. It is afeature of my invention that, by arranging for the two factors to beeffective simultaneaously, I minimize the' time interval betweenpressing of the button 90 andthe 'beginningof flushing discharge. fromthe tank. I have found by' experiments with one of my devices that ifthe' refill tube is plugged or disconnected leaving only the firstfactor operative, the delay in operation is extended to an interval ofeighteen to twenty seconds. If the refill tube is employed Withoutpermitting the water level to rise above normal, in which case only thesecond factor is operative, ow is started after a delay of somethingmore than ten seconds. By arranging for both the factors to be operativesimultaneously, I reduce the time of operation approximately to aninterval of six to ten seconds, depending upon the pressure of the waterin the supply line that is connected to the stand-pipe I4. The delayperiod is also influenced by the rate and velocity of flow through therefill tube and is therefore affected by the diameter of the rell tube.The

ystarting time of six to ten seconds achieved by using, a ve-sixteenthsinch rell tube is increased to an interval of nine to twelve seconds ifa onequarter inch refill tube is substitued.

When the water level drops below the lower end of the vent tube 40, airpasses into the siphon through the vent tube and causes siphonic actionto cease. A feature of my invention is that the vent tube arrangementshown breaks the siphonic flow in a substantially noiselessvmanner.Since a certain time interval is required for sufficient air to passthrough the vent tube to break siphonic flow, the lowest water level 4Iis spaced below the end of the vent tube.

I have found that the quantity of air necessary to serve as an air lockbetween periods of flush tank operation substantially exceeds thequantity of air necessary to break siphonic ow. Because of this fact,and also because some of the air employed to break siphonic ow may becarried through the siphon, it is necessary that air be admitted throughthe vent tube 40 for a substantial period of time after siphonic flowterminates. Since water entering the tank through the pipe I6, however,tends to cause the water level to rise promptly to a level sealing thelower end of the vent tube, some provision must be made to delay suchsealing action. A feature of my invention is the conception that suchprovision may be had by simply adding the screw 12 to depress the valvelever 63 as the water approaches the lowermost level 4I. While it isapparent that the screw 12 could be set to close the valve entirely,thereby making the flush tank inoperative, nevertheless, in practice, Ihave found that there is a considerable range of tolerance for theadjustment of the screw within which range the ilow into the tank willbe throttled near the lowermost water level to retard the rise of thewater suiciently to permit the admission of ample air through the venttube into the air trap space of the siphon. The range of throttled owmay extend from 'the lowermost water level 4I to, for example, a Waterlevel indicated at 96 in Fig. l.

During the period that the water level is rising in the tank, the relltube 43 is continuously discharging water into the down-leg 34 of thesiphon. Between the period that the water level in the tank is risingfrom the lowermost level 4l to the level at which it seals the Vent tube4D, the water supplied by the refill tube lls both the inn-er up-leg andthe intermediate downleg 34 and overflows both into the discharge pipeI8 and into the outer up-leg 33 into the tank proper. The proportion ofthe water that overflows into the pipe I9 during this interval may beincreased either by cutting'away a portion of the upper edge of the Wall2| or by having that upper edge slightly lower than the upper edge ofthe siphon wall 23.

After the vent tube is sealed, the water rising in the vent tube and inthe outer up-leg 33 progressively raises the pressure of the air trappedin the siphon, which rise in pressure depresses the column of water inthe intermediate downleg 34 of the siphon so that all of the subsequentow from the refill tube 43 passes intothe discharge pipe I9, therefilling of the toilet bowl continuing as long as the valve I5 is open.Throughout the period in which the water level in the tank is risingabove the entrance of the vent tube 40, the head of the water in thetank taken at the inlet of the siphon will equal the combined heads ofthe siphon up-legs 33 and 35 less the head of water in the down-leg 34.In the maintenance of such balance during the period of water rise inthe tank, the level of water in the down-leg 34 vwill progressivelydrop, the various elements involved being so dimensioned and disposedthat the nal normal level of the water in the down-leg 34 is relativelyclose to the lower end of the siphon Wall 21. The amount of increase inwater level in the tank above the level 31 necessary to start siphonicaction, ow from the rell tube being disregarded, depends` upon thespacing ofthe water level in the downleg 34 above the bottom edge of theWall 27.

It has been noted that with the normal water levels in the tank and thesiphon legs, ow from the refill tube 43 is effective to initiatesiphonic flow. It is apparent, then, that if water continued to besupplied through the refill tube with full force as the water levelsrise when the tank is being refilled, the ow from the refill tube mightinitiate siphonic flow before the normal water levels are reached. Sucha possibility is precluded, however, by the fact that the nearer thenormal water levels are approached, the more the oat 'l0 reduces owthrough the valve I5. It is significant, then, that at the start of thecycle of flush tank operation, fluid is discharged through the refilltube with full force, but is throttled down at the end of the cycle ofoperation when the normal water levels are being restored, and a featureof my invention is the conception that the diiierence in action of therefill tube at the two ends of the operating cycle makes it practical toemploy the refill tube for initiating siphonic flow. When it isdesirable to destroy the air lock, the rell tube discharges in arelatively violent manner; when, on the contrary, it is desirable toconserve the body of air in the siphon, the refill ow is automaticallysubdued to the required degree.

Various factors determine the effectiveness of the stream dischargedfrom the refill tube. As previously noted, the eiectiveness of the relltube discharge increases with the diameter of the refill tube. Anotherfactor is the `size of the sinuous siphon passage, particularly thatportion constituting the down-leg 34, relative to the volume of refillow. 'I'he effectiveness of the discharge from the rell tube may beattributed to other factors such as the fact that kinetic energy isimparted to the inner up-leg 35 serving to upset equalization of thesiphon head with the tank head, or the fact that the discharge from therefill tube involves a certain Venturi effect that upsets the balance byrelieving the air pressure on the water column in the up-leg 35, or thefact that the stream discharged from the resirable character of flushtank operation.

ll tube entrains air in the air lock delivering the entrained air intothe inner up-leg 35. It is also to be noted that when the mechanism Vistripped to initiate the operating cycle, discharge through the rell tubein full force takes place abruptly and favors ow through the up-leg 35of the siphon rather than in the opposite direction both because of :thedirection in which the l discharge end of the refill tube' is disposedand because the water in the up-leg 35 has less mass and therefore lessinertia than the water inthe opposite direction.

It is within the scope of my conception to design the refill tube forreliance primarily on any one of thesefactors or functions. It isnecessary, of course, that the effectiveness of the refill tube berestricted to a certain range since, on the one hand, `the action mustbe violent enough to initiate siphonic discharge, but, on the otherhand,should not be so violent as to carry air out ofthe siphon while theWater level is rising. Within this range, the adjustment of thedischarge from'the refill tube is not critical. In practice I design therell tube with ample effectiveness in mind and then resort to somesimple expedient for cutting down the electiveness to the requiredoperative range. The provision of the diverting flange 41 on thedischarge end of the refill tube is such anexpedient.

When the push-button is released,y the weight of the angular levercauses the lever'to drop to its normal disposition, forcing thepushbutton outward. 'I'he bell-crank is then free to rotate to itsnormal angular disposition. During the drop in the water level in thetank, the short arm 1| of the float lever rotates upwardly increasingthe distance between the pin 14 on which the bell-crank is pivoted andthe valve lever 63. When this distance exceeds the length of the shortarm 15 of the bell-crank, including the roll-er on the end of the arm,the preponderant weight of the longer arm 'I6 of the bell-crank causesthe bell-crank to rotate carrying the roller 19 against the bracket 52as shown in vdotted lines in Fig. 1. 'I'he bell-crank is .then in aneffective disposition for depressing the valve lever 63 to close thevalve as the iioa't 10 moves upward with the rising Water level. Thenormal water level may, ofcourse, be varied by adjusting the screw 65.

The purpose of Fig. 7 is to indicate some of the modifications that maybe made in my invention, prime numbers being employedy to designateelements corresponding to elements in the preferred form previouslydescribed. It will be noted that the refill tube 43 has an unimpededdischarge end. 'I'he kinetic energy of the vdischarge fromfthis tube is,however, dissipated to a desirable extent by a small baie 93 in the pathof the discharge stream. It will be further noted that the vent tube isomitted, the function of the vent tube being provided by a small ventaperture 99 in the outer siphon wall 28.

Such a vent aperture is fully as effective as the vent tube arrangement,but is not as quiet in operation.

The features of the arrangement shown and described combine xandcooperate to provide ade- The Water is discharged with adequate forceand rapidity, buty with substantially none of the noise thatcharacterizes the usual ush tank operation. The construction is notsusceptible to break-down and no attention nor adjustments are necessaryto maintain theush tank in service. A noteworthy feature is the absenceof any type of discharge valve for the tank. The only parts subject towear are those functionally related to the inlet valve to the tank.

For the purpose of this disclosure and to illustrate the principlesinvolved, I have described a preferred embodiment of my invention inspecific detail, but those skilled in the art will realize that variouschanges `and modifications may be made without departing from theessence of my concept. I reserve the right to all such changes andmodifications that lproperly come within the scope of my appendedclaims.

I claim as my invention:

1. The combination with a flush tank having a discharge port, a liquidsupply means, a valve for the supply means, and automatic means forclosing said valve when liquid in the tank rises to a normal level, of:a normally sunbmerged discharge siphon leading to said discharge port,said siphon having a passage providing an outer upleg, an inner up-legand an intermediate downleg whereby air trapped above the outer up-legand in the intermediate down-leg cooperates with the liquid in the twoup-legs to balance the normal head of liquid in the tank; and means todischarge liquid downwardly into said down-leg of the siphon to initiatesiphonic flow from the tank.

2. The combination with a flush tank having a discharge port, a supplypipe, a valve for the supply pipe, and a iioat, of: means to operativelyconnect said float with said valve to close the valve as 4the liquidlevel in the tank rises to a normal level, said means being movablebetween effective and ineffective dispositions and being adapted when inthe ineffective disposition with the float at normal level to moveautomatically to the effective disposition when the float de- 40 scendssubstantially below the normal level; a

normally submerged discharge siphon leading to said discharge port, saidsiphon having a passage providing an outer up-leg, an inner up-leg andan intermediate down-leg whereby air trapped i54 above the outer up-legand in the intermediate down-leg cooperates with the liquid in the twoup-legs to balance the normal head of liquid in the tank; a vent tubeextending from the interior of said siphon to a level near but above theinlet end of said outer up-leg of the siphon, said vent tube beingdisposed to communicate with the space in the siphon occupied by saidtrapped air to break flow from the siphon with relatively little noisebefore the water level reaches said lower end of said outer up-leg ofthe siphon; and means adapted `to operatively connect said float withsaid valve to partially close the valve as the liquid level in the tankapproaches its lower-most level below the lower end of said vent tube todelay the subsequent rise of the liquid level to permit air to flowthrough said tube into the siphon for a substantial time interval.

3. The combination with a flush tank having a discharge port, aliquid-supply valve, and automatic means for closing said valve whenliquid in the tank rises to a normal level, of: a normally submergedsinuous discharge siphon communieating with said port, said siphonhaving two uplegs and providing an air trap intermediate the two up-legswhereby the combined heads of said up-legs balance the normal pressureof liquid submerging the siphon; siphon-initiating means fed by thesupply stream from said valve to discharge liquid into said siphon at arate, velocity, and direction to destroy said air trap and initiatesiphonic discharge from the tank; and means to throttle down said valveas the liquid in the tank rises to normal, whereby the liquid streamdischarged into said siphon by said siphon-initiating means is throttledas the combined heads of said up-legs approach balance with the normalhead of the liquid sub-merging the siphon.

4. 'Ihe combination with a flush tank having a discharge port, aliquid-supply valve, and automatic means for closing said valve whenliquid in the tank rises to a normal level, of: a normally submergedsinuous discharge siphon communieating with said port, said siphonhaving two uplegs and providing an air trap intermediate the two up-legswhereby the combined heads of said up-legs balance the normal pressureof liquid submerging the siphon; means to discharge a stream of liquidinto said siphon .at a rate, velocity, and direction to destroy said airtrap and initiate siphonic discharge from the tank; and means todissipate at least a portion of the kinetic energy of said stream tokeep said stream from forcing air from the air trap when the tank isbeing refilled.

5. The combination of a nush tank having a discharge port, and supplymeans to deliver a stream of liquid into the tank when the liquid in thetank is below la normal level, of a normally submerged sinuous dischargesiphon communieating with said port, said siphon having two uplegs andproviding an air tra-p intermediate the two up-legs whereby the combinedheads of said up-legs balance the normal pressure of liquid submergingthe siphon; a vent tube extending from the interior of said siphon to alevel near but above the inlet end of said siphon, said vent tube beingdisposed to communicate with said air trap to break flow from the siphonwith relatively little noise before the liquid level drops to said inletend of the siphon; and means to throttle iiow into the tank from saidsupply means when the liquid level in the tank drops below the lower endof said vent tube thereby to provide .a substantial time interval forair to flow through said tube into the siphon.

6. The combination with a flush tank having a discharge port, a liquidsupply means, a valve for the supply means, and automatic means forclosing said vialve when liquid in the tank rises to a normal level, of:a normally submerged sinuous discharge siphon communicating with saidport, said siphon having two up-legs and providing an air trapintermediate the two up-legs whereby the combined heads of said up-legsbalance the normal pressure of liquid submerging the siphon; a vent tubeextending from the interior of said siphon to a level near but above theinlet end of said siphon, said vent tube being disposed to communicatewith said air trap to break flow from the siphon with relatively littlenoise before the liquid level drops to said inlet end of the siphon; andautomatic means constructed and arranged to partially close said valvewhen the liquid level in the tank is below the lower end of said venttube to provide a substantial time interval for air to pass into thesiphon through said vent tube.

WILLIAM J. COLLISON.

